Stator vane support system within a gas turbine engine

ABSTRACT

A stator vane segment ( 10 ) including a connection system ( 12 ) that enables stator vane ( 14 ) alignment while enabling an individual stator vane ( 14 ) to be replaced is disclosed. The stator vane connection system ( 12 ) may include a radially extending inner support ( 26 ) extending from a stator vane ( 14 ), whereby the inner support ( 26 ) is secured to forward and aft inner rings via a removable, inner axial bolt ( 22 ). The stator vane connection system ( 12 ) may include one or more first inner pins ( 24 ) that aligns the stator vane ( 14 ) and is positioned within the portion of the inner support ( 26 ) of the stator vane ( 14 ) to which one or more inner axial bolts ( 22 ) are attached. The stator vane connection system ( 12 ) may include one or more first outer alignment pins ( 28 ) that aligns the stator vane ( 14 ) and is positioned within a portion of the outer diameter platform ( 48 ) of the stator vane ( 14 ), whereby the first outer alignment pin ( 28 ) aligns the stator vane ( 14 ).

FIELD OF THE INVENTION

This invention is directed generally to stator vane airfoils within gasturbine engines, and more particularly to support systems for statorvane airfoils.

BACKGROUND

Turbine engines typically include a plurality of rows of stationarycompressor stator vanes extending radially inward from a shell andinclude plurality of rows of rotatable compressor blades attached to arotor assembly for turning the rotor. Conventional turbine engines ofteninclude a segment with multiple stationary airfoils collectivelyreferred to as a stator. Stator segments deflect in the upstreamdirection under steady gas pressure loading, and the deflection variesaround the circumference dependent upon how the segment is constrainedto the casing. The unconstrained ends of the segment deflect more andhave less axial clearance to the upstream rotor disk. Thus, a needexists to control deflection and alignment of the stator vane airfoilsforming the stator.

SUMMARY OF THE INVENTION

A compressor stator vane segment including a connection system thatenables stator vane alignment while enabling an individual stator vaneto be replaced is disclosed. The stator vane connection system mayinclude a radially extending inner support extending from a stator vane,whereby the inner support is secured to forward and aft inner rings viaa removable, inner axial bolt. The stator vane connection system mayinclude one or more first inner pins that aligns the stator vane and ispositioned within the portion of the inner support of the stator vane towhich one or more inner axial bolts are attached. The stator vaneconnection system may include one or more first outer alignment pinsthat aligns the stator vane and is positioned within the portion of theouter diameter platform of the stator vane, whereby the first outeralignment pin aligns the stator vane.

The compressor stator vane segment may be formed from a stator vaneincluding an airfoil formed from an outer wall, and having a leadingedge, a trailing edge, a pressure side, a suction side, an innerdiameter platform at a first end of the airfoil, and an outer diameterplatform at a second end of the airfoil. The compressor stator vanesegment may include a stator vane connection system. The stator vaneconnection system may be formed from one or more inner axial boltsextending through a first inner ring, through at least a portion of aninner support of the stator vane positioned inward of the airfoil, andinto a second inner ring to secure the stator vane. At least one firstinner pin may be positioned within the portion of the inner support ofthe stator vane to which the inner axial bolt is attached. The firstinner pin may align the stator vane relative to an adjacent stator vane.One or more first outer alignment pins may be positioned within theportion of the outer diameter platform of the stator vane, whereby thefirst outer pin aligns the stator vane relative to an adjacent statorvane.

The stator vane connection system may also include an outer tie barcoupled to the outer diameter platform. The outer tie bar may be securedto the outer diameter platform via a removable connection system, suchas, but not limited to, a dovetail connection and one or more radiallyextending bolts between the outer tie bar and the outer diameterplatform. In at least one embodiment, the first inner ring may be aforward inner ring. One or more seals may extend radially inward from aradially inner surface of the forward inner ring. The seal extendingradially inward from a radially inner surface of the forward inner ringmay be a honeycomb seal. The forward inner ring may be sized to fitradially inward of a forward extending portion of the inner diameterplatform and within a recess in the inner diameter platform. In at leastone embodiment, the second inner ring may be an aft inner ring. One ormore seals may extend radially inward from a radially inner surface ofthe aft inner ring. The seal extending radially inward from a radiallyinner surface of the aft inner ring may be a honeycomb seal.

In at least one embodiment, an outer surface of the aft inner ring maybe flush with a radially outer surface of the inner diameter platform ofthe airfoil. The aft inner ring may include a portion that is sized toextend axially forward into an aft recess in the inner diameterplatform. The aft inner ring may also include two aft extending armsseparated from each other via an aft recess. A radially inner surface ofthe inner support of the stator vane may be flush with a radially innersurface of the first inner ring and a radially inner surface of thesecond inner ring. In at least one embodiment, the first inner pin maybe positioned within the portion of the inner support of the stator vaneand may extend in a circumferential direction, and one or more secondinner pins may be positioned within the portion of the second inner ringand may extend in a circumferential direction. The inner axial bolt mayinclude threads that engage threads within the second inner ring. Theinner axial bolt may include a head that is larger than a shaft of theaxial bolt, and the first inner ring may include a head receiving cavityin which the head of the inner axial bolt resides.

The compressor stator vane segment may be assembled in a number of ways.In at least one embodiment, the compressor stator vane segment may beassembled by milling the airfoil, coating the airfoil flow pathsurfaces, turning the outer ring from a rolled ring, turning the forwardinner ring from a custom forging, turning the aft inner ring from acustom forging, drilling holes in the outer ring, drilling holes in theinner forward ring, drilling holes in the aft inner ring, brazing aforward honeycomb seal to the forward inner ring, brazing an afthoneycomb seal to the aft inner ring, turning the forward honeycombinner diameter, turning the aft honeycomb inner diameter, sawing theouter ring in half, sawing the forward inner ring in half, sawing theaft inner ring in half, and assembling the stator vanes and rings withbolts and pins and stake the fasteners. Formation of the compressor vanesegment in this manner, reduces the number of manufacturing steps byseven steps in comparison to conventional systems.

An advantage of the compressor stator vane segment is that thecompressor stator vane segment enables individual airfoil replacementwithout cutting or welding during outages or other times.

Another advantage of the compressor stator vane segment is that fewercustom made parts, such as in one embodiment, three fewer custom madeparts, are needed than in conventional systems.

Yet another advantage of the compressor stator vane segment is that thecompressor stator vane segment may be formed with fewer manufacturingsteps, such as in one embodiment, seven fewer steps, are needed than inconventional systems.

Still another advantage of the compressor stator vane segment is thatwelding and stress relieving are not required.

Another advantage of the compressor stator vane segment is thatmachining of the entire assembly is not required, which reduces liftingtime and equipment costs.

Yet another advantage of the compressor stator vane segment is thatcoating of the entire assembly is not required, which reduces liftingtime, shipping and equipment costs.

Still another advantage of the compressor stator vane segment is thatinner rings may be formed from a lower cost material, such as, but notlimited to, low carbon steel, than conventional systems.

Another advantage of the compressor stator vane segment is that a coverhalf and a base half may be interchangeable between engines, whichreduces service inventory and handling costs.

Yet another advantage of the compressor stator vane segment is that thesegment could be formed in 90 degree segments to further reduce serviceinventory and handling costs and for ease of assembly and disassembly.

Still another advantage of the compressor stator vane segment is thatmechanical dampening may be achieved through use of the bolted assembly.

These and other embodiments are described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate embodiments of the presently disclosedinvention and, together with the description, disclose the principles ofthe invention.

FIG. 1 is a perspective view of compressor stator vane segment within agas turbine engine.

FIG. 2 is a cross-sectional view of a compressor stator vane segmentwithin a gas turbine engine taken at section line 2-2 in FIG. 1.

FIG. 3 is a detail view of a portion of the compressor stator vanesegment within a gas turbine engine taken at detail line 3-3 in FIG. 2.

FIG. 4 is an end view of two compressor stator vane segments forming asingle stage stator assembly.

FIG. 5 is an end view of another embodiment of compressor stator vanesegments forming a single stage stator assembly, whereby four statorvane segments are used.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1-5, a compressor stator vane segment 10 including aconnection system 12 that enables stator vane alignment while enablingan individual stator vane 14 to be replaced is disclosed. The statorvane connection system 12 may include a radially extending inner support16 extending from a stator vane 14, whereby the inner support 16 issecured to forward and aft inner rings 18, 20 via a removable, inneraxial bolt 22. The stator vane connection system 12 may include one ormore first inner pins 24 that aligns the stator vane 14 and ispositioned within the portion of the inner support 16 of the stator vane14 to which one or more inner axial bolts 22 are attached. The statorvane connection system 12 may include one or more first outer alignmentpins 28 that aligns the stator vane 14 and is positioned within theportion of the outer diameter platform 30 of the stator vane 14, wherebythe first outer alignment pin 28 aligns the stator vane 14. In at leastone embodiment, the compressor stator vane segment 10 may include astator vane 14 formed from an airfoil 32 formed from an outer wall 34,and having a leading edge 36, a trailing edge 38, a pressure side 40, asuction side 42, and an inner diameter platform 44 at a first end 46 ofthe airfoil 32 and an outer diameter platform 30 at a second end 50 ofthe airfoil 32. The stator vane 14 may be secured with the turbineengine 54 via a stator vane connection system 12. The stator vaneconnection system 12 may be formed from one or more inner axial bolts 22extending through a first inner ring 18, through at least a portion ofan inner support 16 of the stator vane 14 positioned inward of theairfoil 32, and into a second inner ring 20 to secure the stator vane14. In at least one embodiment, the first inner ring 18 is a forwardinner ring 18, and the second inner ring 20 is an aft inner ring 20. Oneor more first inner pins 24 may be positioned within the portion of theinner support 16 of the stator vane 14 to which the inner axial bolt 22is attached. The first inner pin 24 may align the stator vane 14relative to an adjacent stator vane 14. The stator vane connectionsystem 12 may also include on or more first outer alignment pins 28positioned within the portion of the outer diameter platform 30 of thestator vane 14. The first outer pin 24 aligns the stator vane 14relative to an adjacent stator vane 14.

The stator vane connection system 12 may also include an outer tie bar56 coupled to the outer diameter platform 30. The outer tie bar 56 maybe secured to the outer diameter platform 30 via a removable connectionsystem 58, such as, but not limited to, a dovetail connection 58. Theouter tie bar 56 may be configured to have a dovetail shape extending ina circumferential direction such that it includes an linear outersurface 70 with inwardly sloped sidewalls 72, 74. In addition, the outerdiameter platform 30 may have a dovetail shaped receiver 62 with alinear base surface 64 and inward sloped sidewalls 66 and 68. The outertie bar 56 may also be coupled to the stator vane 14 via one or moreradially extending bolts 60 between the outer tie bar 56 and the outerdiameter platform 30.

The stator vane connection system 12 may also include one or moreforward seals 76 extending radially inward from a radially inner surface78 of the forward inner ring 18. In at least one embodiment, the forwardseal 76 may be, but is not limited to being, a honeycomb seal or a knifeseal. The forward inner ring 18 may be is sized to fit radially inwardof a forward extending portion 80 of the inner diameter platform 44 andwithin a recess 82 in the inner diameter platform 44. The forwardsurface 84 of the forward inner ring 18 may be flush with a forwardsurface 86 of the inner diameter platform 44.

The stator vane connection system 12 may also include one or more aftseals 88 extending radially inward from a radially inner surface 90 ofthe aft inner ring 20.

In at least one embodiment, the aft seal 88 may be, but is not limitedto being, a honeycomb seal or a knife seal. In at least one embodiment,an outer surface 92 of the aft inner ring 20 may be flush with aradially outer surface 94 of the inner diameter platform 44 of theairfoil 32. The aft inner ring 20 may include a forward portion 96 thatis sized to extend axially forward into an aft recess 98 in the innerdiameter platform 44. The aft inner ring 20 may also include two aftextending arms 100, 102 and separated from each other via an aft recess104. In at least one embodiment, a radially inner surface 106 of theinner support 16 of the stator vane 14 may be flush with a radiallyinner surface 108 of the first inner ring 18 and a radially innersurface 110 of the second inner ring 20.

On or more first inner pins 24 positioned within the portion of theinner support 16 of the stator vane 14 extends in a circumferentialdirection. One or more second inner pins 112 may be positioned withinthe portion of the second inner ring 20 and may extend in acircumferential direction. The first inner pin 24 or the second innerpin 112 or both may be positioned generally orthogonal to a longitudinalaxis 114 of a turbine engine 54. The first inner pin 24 and the secondinner pin 112 may have any appropriate shape and length. In at least oneembodiment, the first inner pin 24 or the second inner pin 112, or bothmay be generally cylindrical. The first inner pin 24 and the secondinner pin 112 may be formed from any appropriate material. The

The inner axial bolt 22 may include threads 116 that engage threads 118within the second inner ring 20. The inner axial bolt 22 may alsoinclude a head 120 that is larger than a shaft 122 of the axial bolt 22.The first inner ring 18 may include a head receiving cavity 124 in whichthe head 120 of the inner axial bolt 22 resides.

The compressor stator vane segment 10 may be assembled in a number ofways. In at least one embodiment, the compressor stator vane segment 10may be assembled by milling the airfoil 32, coating the airfoil flowpath surfaces, turning the outer ring from a rolled ring, turning theforward inner ring 18 from a custom forging, turning the aft inner ring20 from a custom forging, drilling holes in the outer ring, drillingholes in the inner forward ring 18, drilling holes in the aft inner ring20, brazing a forward honeycomb seal 76 to the forward inner ring 18,brazing an aft honeycomb seal 88 to the aft inner ring 20, turning theforward honeycomb inner diameter, turning the aft honeycomb innerdiameter, sawing the outer ring in half, sawing the forward inner ring18 in half, sawing the aft inner ring 20 in half, and assembling thestator vanes 14 and rings 18, 20 with bolts 22, 60 and pins 24, 28, 112and staking the fasteners.

The foregoing is provided for purposes of illustrating, explaining, anddescribing embodiments of this invention. Modifications and adaptationsto these embodiments will be apparent to those skilled in the art andmay be made without departing from the scope or spirit of thisinvention.

We claim:
 1. A stator vane segment (10), characterized in that: a statorvane (14) formed from an airfoil (32) formed from an outer wall (34),and having a leading edge (36), a trailing edge (38), a pressure side(40), a suction side (42), an inner diameter platform (44) at a firstend (46) of the airfoil (32) and an outer diameter platform (48) at asecond end (50) of the airfoil (32); a stator vane connection system(12) comprising: at least one inner axial bolt (22) extending through afirst inner ring (18), through at least a portion of an inner support(26) of the stator vane (14) positioned inward of the airfoil (32), andinto a second inner ring (20) to secure the stator vane (14); at leastone first inner pin (24) positioned within the portion of the innersupport (26) of the stator vane (14) to which the at least one inneraxial bolt (22) is attached, wherein the at least one first inner pin(24) aligns the stator vane (14); and at least one first outer alignmentpin (28) positioned within the portion of the outer diameter platform(48) of the stator vane (14), wherein the at least one first outer pin(28) aligns the stator vane (14).
 2. The stator vane segment (10) ofclaim 1, further characterized in that an outer tie bar (56) coupled tothe outer diameter platform (48), wherein the outer tie bar (56) issecured to the outer diameter platform (48) via a dovetail connection(58) and at least one radially extending bolt between the outer tie bar(56) and the outer diameter platform (48).
 3. The stator vane segment(10) of claim 1, characterized in that the first inner ring (18) is aforward inner ring (18).
 4. The stator vane segment (10) of claim 3,further characterized in that a seal (76) extending radially inward froma radially inner surface of the forward inner ring.
 5. The stator vanesegment (10) of claim 4, characterized in that the seal (76) extendingradially inward from a radially inner surface of the forward inner ringis a honeycomb seal (76).
 6. The stator vane segment (10) of claim 3,characterized in that the forward inner ring is sized to fit radiallyinward of a forward extending portion of the inner diameter platform(44) and within a recess in the inner diameter platform (44).
 7. Thestator vane segment (10) of claim 1, characterized in that the secondinner ring (20) is an aft inner ring (20).
 8. The stator vane segment(10) of claim 7, further characterized in that a seal (88) extendingradially inward from a radially inner surface (90) of the aft inner ring(20).
 9. The stator vane segment (10) of claim 8, characterized in thatthe seal (88) extending radially inward from a radially inner surface(90) of the aft inner ring (20) is a honeycomb seal (88).
 10. The statorvane segment (10) of claim 7, characterized in that an outer surface(92) of the aft inner ring (20) is flush with a radially outer surface(94) of the inner diameter platform (44) of the airfoil (32).
 11. Thestator vane segment (10) of claim 7, characterized in that the aft innerring (20) includes a portion that is sized to extend axially forwardinto an aft recess (98) in the inner diameter platform (44).
 12. Thestator vane segment (10) of claim 7, characterized in that the aft innerring (20) includes two aft extending arms (100, 102) and separated fromeach other via an aft recess (104).
 13. The stator vane segment (10) ofclaim 1, characterized in that a radially inner surface (106) of theinner support (26) of the stator vane (14) is flush with a radiallyinner surface (108) of the first inner ring (18) and a radially innersurface (110) of the second inner ring (20).
 14. The stator vane segment(10) of claim 1, characterized in that the at least one first inner pin(24) positioned within the portion of the inner support (26) of thestator vane (14) extends in a circumferential direction and at least onesecond inner pin (112) positioned within the portion of the second innerring (20) and extending in a circumferential direction.
 15. The statorvane segment (10) of claim 1, characterized in that the at least oneinner axial bolt (22) includes threads (116) that engage threads (118)within the second inner ring (20).
 16. The stator vane segment (10) ofclaim 1, characterized in that the at least one inner axial bolt (22)includes a head (120) that is larger than a shaft (122) of the axialbolt (22) and wherein the first inner ring (18) includes a headreceiving cavity (124) in which the head 912) of the inner axial bolt(22) resides.